Antibiotic IV to PO Switch 💊
Reference table for switching from intravenous to oral antimicrobials. Includes dosing conversions, bioavailability considerations, and clinical notes based on HSE AMRIC guidelines.
💡 Overview
- Switching from IV to oral antibiotics when appropriate improves patient care and reduces costs.
- Consider switch when patient is clinically stable, able to take oral medications, and has good GI absorption.
- Always review bioavailability, drug interactions, and patient-specific factors before switching.
- Based on HSE AMRIC guidelines for antimicrobial stewardship and IV to oral switch protocols.
✅ Switch Criteria
- Patient clinically stable with improving vital signs
- Able to take oral medications (no vomiting, good GI function)
- Good oral bioavailability of the chosen antibiotic
- No significant drug interactions or absorption issues
- Patient compliance with oral regimen can be ensured
⚠️ Important Considerations
- Doses are for normal renal and hepatic function - adjust as needed
- Oral bioavailability may differ between tablets/capsules and suspensions
- Some antibiotics must be taken on empty stomach for optimal absorption
- Review drug and food interactions before prescribing
- Consider severity of infection when determining appropriate dosing
- Consult pharmacy or microbiology for complex cases
📋 Common Switch Patterns
- Same dose: Amoxicillin, clarithromycin, levofloxacin, linezolid
- Reduced dose: Clindamycin (300-450mg vs 600mg-1.2g), flucloxacillin (500mg-1g vs 1-2g)
- Different drug: Benzylpenicillin → Amoxicillin or Phenoxymethylpenicillin
- Not recommended: Cefuroxime, ceftriaxone, piperacillin-tazobactam (poor oral bioavailability)
- Special considerations: Ciprofloxacin (avoid with enteral nutrition), metronidazole (slightly reduced dose)
Antibiotic IV to PO Switch
Recommended oral agents when switching from IV to oral antimicrobials
Important Notes:
- Doses included are for normal renal & hepatic function
- Doses are for oral capsules/tablets unless otherwise specified
- Review drug and food interactions. Some antimicrobials need to be taken on an empty stomach
- Doses may need to be adjusted according to severity of infection
- See Eolas Medical/BNF/SmPC or seek pharmacist advice regarding dose adjustments
- Based on HSE AMRIC guidelines for antimicrobial stewardship and IV to oral switch protocols
| IV Antimicrobial | IV Dose | Oral Switch Option/Dose | Notes |
|---|---|---|---|
| Amoxicillin | 500mg – 1g q8h (max 12g/day IV) | 500mg – 1g q8h | Same dose for oral switch |
| Benzylpenicillin | 1.2g-2.4g q4-6h | Amoxicillin 500mg – 1g q8h (preferred) OR Phenoxymethylpenicillin: 666mg q6h (Calvepen®) OR 500mg q6h (Kopen®) | Switch to amoxicillin or phenoxymethylpenicillin |
| Cefuroxime | 750mg-1.5g q8h | Not advised | Poor oral bioavailability. Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist |
| Ceftriaxone | 2g q12h/24h | No direct alternative | Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist |
| Ciprofloxacin | 400mg q8-12h | 500mg-750mg q12h | If on enteral nutrition, IV ciprofloxacin preferable to oral as bioavailability may be decreased |
| Clarithromycin | 500mg q12h | 500mg q12h | Same dose for oral switch |
| Clindamycin | 600mg – 1.2g q6h | 300mg - 450mg q6h | Reduced dose for oral administration |
| Co-amoxiclav | 1.2g q8h | 500mg/125mg (625mg) – 875mg/125mg (1g) q8h | For 875mg/125mg (1g) q8h please prescribe as 875mg/125mg q8h |
| Co-trimoxazole | Indication specific | Same dose | Dose depends on indication |
| Flucloxacillin | 1-2g q6h | 500mg - 1g q6h | Reduced dose for oral administration |
| Fluconazole | Indication specific | Same dose | Dose depends on indication |
| Isavuconazole | 200mg q8h for 48h, then 200mg q24h | Same dose | Same dose for oral switch |
| Levofloxacin | 500mg q12h/24h | Same dose | Same dose for oral switch |
| Linezolid | 600mg q12h | Same dose | Same dose for oral switch |
| Metronidazole | 500mg q8h | 400mg q8h | Slightly reduced dose for oral administration |
| Piperacillin-tazobactam | 4.5g q8h/6h | No direct alternative | Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist |
| Rifampicin | Indication specific | Same dose | Dose depends on indication |
| Voriconazole | 6mg/kg q12h for 24h, then 4mg/kg q12h | Patients >40kg: 400mg q12h for 2 doses (if loading required) then 200mg q12h | Dose may be adjusted based on therapeutic drug monitoring results |
Amoxicillin
Switch AvailableIV Dose:500mg – 1g q8h (max 12g/day IV)
Oral Switch:500mg – 1g q8h
Notes: Same dose for oral switch
Benzylpenicillin
Switch AvailableIV Dose:1.2g-2.4g q4-6h
Oral Switch:Amoxicillin 500mg – 1g q8h (preferred) OR Phenoxymethylpenicillin: 666mg q6h (Calvepen®) OR 500mg q6h (Kopen®)
Notes: Switch to amoxicillin or phenoxymethylpenicillin
Cefuroxime
Not advisedIV Dose:750mg-1.5g q8h
Oral Switch:Not advised
Notes: Poor oral bioavailability. Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Ceftriaxone
No direct alternativeIV Dose:2g q12h/24h
Oral Switch:No direct alternative
Notes: Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Ciprofloxacin
Switch AvailableIV Dose:400mg q8-12h
Oral Switch:500mg-750mg q12h
Notes: If on enteral nutrition, IV ciprofloxacin preferable to oral as bioavailability may be decreased
Clarithromycin
Switch AvailableIV Dose:500mg q12h
Oral Switch:500mg q12h
Notes: Same dose for oral switch
Clindamycin
Switch AvailableIV Dose:600mg – 1.2g q6h
Oral Switch:300mg - 450mg q6h
Notes: Reduced dose for oral administration
Co-amoxiclav
Switch AvailableIV Dose:1.2g q8h
Oral Switch:500mg/125mg (625mg) – 875mg/125mg (1g) q8h
Notes: For 875mg/125mg (1g) q8h please prescribe as 875mg/125mg q8h
Co-trimoxazole
Switch AvailableIV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Flucloxacillin
Switch AvailableIV Dose:1-2g q6h
Oral Switch:500mg - 1g q6h
Notes: Reduced dose for oral administration
Fluconazole
Switch AvailableIV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Isavuconazole
Switch AvailableIV Dose:200mg q8h for 48h, then 200mg q24h
Oral Switch:Same dose
Notes: Same dose for oral switch
Levofloxacin
Switch AvailableIV Dose:500mg q12h/24h
Oral Switch:Same dose
Notes: Same dose for oral switch
Linezolid
Switch AvailableIV Dose:600mg q12h
Oral Switch:Same dose
Notes: Same dose for oral switch
Metronidazole
Switch AvailableIV Dose:500mg q8h
Oral Switch:400mg q8h
Notes: Slightly reduced dose for oral administration
Piperacillin-tazobactam
No direct alternativeIV Dose:4.5g q8h/6h
Oral Switch:No direct alternative
Notes: Discuss suitable oral alternatives with microbiology/infectious diseases/antimicrobial pharmacist
Rifampicin
Switch AvailableIV Dose:Indication specific
Oral Switch:Same dose
Notes: Dose depends on indication
Voriconazole
Switch AvailableIV Dose:6mg/kg q12h for 24h, then 4mg/kg q12h
Oral Switch:Patients >40kg: 400mg q12h for 2 doses (if loading required) then 200mg q12h
Notes: Dose may be adjusted based on therapeutic drug monitoring results
References:
HSE AMRIC:Intravenous to Oral Switch Toolkit (February 2025)
This table is based on the official HSE AMRIC guidelines for antimicrobial stewardship and IV to oral switch protocols.
Educational reference only. Medical disclaimer